org.eclipse.mylyn.commons.ui/src/org/eclipse/mylyn/commons/ui/AbstractColumnViewerSupport.java - mylyn/org.eclipse.mylyn.commons - Git at Google

 /*******************************************************************************
  * Copyright (c) 2010, 2011 Tasktop Technologies and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
  * https://www.eclipse.org/legal/epl-2.0
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  *     Tasktop Technologies - initial API and implementation
  *******************************************************************************/

 package org.eclipse.mylyn.commons.ui;

 import java.io.File;
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.jface.layout.AbstractColumnLayout;
 import org.eclipse.jface.util.Policy;
 import org.eclipse.jface.viewers.ColumnLayoutData;
 import org.eclipse.jface.viewers.ColumnPixelData;
 import org.eclipse.jface.viewers.ColumnViewer;
 import org.eclipse.jface.viewers.ColumnWeightData;
 import org.eclipse.mylyn.commons.core.XmlMemento;
 import org.eclipse.mylyn.internal.commons.ui.Messages;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.DisposeEvent;
 import org.eclipse.swt.events.DisposeListener;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.events.SelectionListener;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Item;
 import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.Menu;
 import org.eclipse.swt.widgets.MenuItem;

 /**
  * Provides an abstract implementation for persisting the column and sorting state of a {@link ColumnViewer}.
  *
  * @author Shawn Minto
  * @author Steffen Pingel
  * @since 3.7
  */
 public abstract class AbstractColumnViewerSupport<T extends Item> {

 	private static class ColumnState {
 		// this represents the width of the column or the weight if it was weight data
 		int width;
 	}

 	public static final String KEY_COLUMN_CAN_HIDE = "org.eclipse.mylyn.column.viewer.support.column.can.hide"; //$NON-NLS-1$

 	// from AbstractColumnLayout
 	private static final String KEY_LAYOUT_DATA = Policy.JFACE + ".LAYOUT_DATA"; //$NON-NLS-1$

 	public static final String KEY_SUPPORTS_SORTING = "org.eclipse.mylyn.column.viewer.support.sorting"; //$NON-NLS-1$

 	private Menu contextMenu;

 	private final Control control;

 	private int[] defaultOrder;

 	private ColumnState[] defaults;

 	private int defaultSortColumnIndex;

 	private int defaultSortDirection;

 	private final boolean[] defaultVisibilities;

 	private final Menu headerMenu;

 	private ColumnState[] lastStates;

 	private final File stateFile;

 	private boolean supportsSorting;

 	private final ColumnViewer viewer;

 	public AbstractColumnViewerSupport(ColumnViewer viewer, File stateFile) {
 		this(viewer, stateFile, new boolean[0]);
 	}

 	public AbstractColumnViewerSupport(ColumnViewer viewer, File stateFile, boolean[] defaultVisibilities) {
 		Assert.isNotNull(viewer);
 		Assert.isNotNull(stateFile);
 		Assert.isNotNull(defaultVisibilities);
 		Object supportSort = viewer.getControl().getData(KEY_SUPPORTS_SORTING);
 		if (supportSort instanceof Boolean) {
 			supportsSorting = (Boolean) supportSort;
 		} else {
 			supportsSorting = true;
 		}
 		this.defaultVisibilities = defaultVisibilities;
 		this.viewer = viewer;
 		this.stateFile = stateFile;

 		control = viewer.getControl();

 		Composite parent = viewer.getControl().getParent();
 		headerMenu = new Menu(parent);
 	}

 	abstract void addColumnSelectionListener(T column, SelectionListener selectionListener);

 	private MenuItem createMenuItem(Menu parent, final T column, final int i) {
 		final MenuItem item = new MenuItem(parent, SWT.CHECK);
 		item.setText(column.getText());
 		item.setSelection(getWidth(column) > 0);
 		item.addListener(SWT.Selection, new Listener() {
 			public void handleEvent(Event event) {
 				int lastWidth = getWidth(column);
 				if (lastWidth != 0) {
 					lastStates[i].width = lastWidth;
 				}
 				if (lastStates[i].width == 0) {
 					// if the user shrunk it to 0, use the default
 					lastStates[i].width = defaults[i].width;
 				}
 				if (lastStates[i].width == 0) {
 					// if the default and the last width was 0, then set to 150 pixels
 					lastStates[i].width = 150;
 				}
 				if (item.getSelection()) {
 					setWidth(column, lastStates[i].width);
 				} else {
 					setWidth(column, 0);
 				}
 			}
 		});
 		return item;
 	}

 	private void createRestoreDefaults(Menu parent) {

 		new MenuItem(parent, SWT.SEPARATOR);

 		final MenuItem restoreDefaults = new MenuItem(parent, SWT.PUSH);
 		restoreDefaults.setText(Messages.AbstractColumnViewerSupport_Restore_defaults);
 		restoreDefaults.addListener(SWT.Selection, new Listener() {
 			public void handleEvent(Event event) {
 				restoreDefaults();
 			}
 		});
 	}

 	abstract Rectangle getClientArea();

 	abstract T getColumn(int index);

 	abstract int getColumnIndexOf(T column);

 	abstract AbstractColumnLayout getColumnLayout();

 	private ColumnLayoutData getColumnLayoutData(Item column) {
 		Object data = column.getData(KEY_LAYOUT_DATA);
 		if (data instanceof ColumnLayoutData) {
 			return (ColumnLayoutData) data;
 		} else {
 			return null;
 		}
 	}

 	abstract int[] getColumnOrder();

 	abstract T[] getColumns();

 	abstract int getColumnWidth(T column);

 	abstract int getHeaderHeight();

 	abstract T getSortColumn();

 	abstract int getSortDirection();

 	private int getWidth(T column) {
 		ColumnLayoutData data = getColumnLayoutData(column);
 		AbstractColumnLayout columnLayout = getColumnLayout();
 		if (data != null && columnLayout != null) {
 			if (data instanceof ColumnWeightData) {
 				return ((ColumnWeightData) data).weight;
 			} else if (data instanceof ColumnPixelData) {
 				// turn this into a weighted width
 				int width = ((ColumnPixelData) data).width;
 				int totalWidth = control.getSize().x;
 				if (totalWidth == 0) {
 					return width;
 				} else {
 					return (width * 100) / totalWidth;
 				}
 			} else {
 				// we dont know
 				return getColumnWidth(column);
 			}
 		} else {
 			// if has column data, use that (pixel or weight)
 			return getColumnWidth(column);
 		}
 	}

 	private void initialize() {
 		T[] columns = getColumns();
 		defaults = new ColumnState[columns.length];
 		defaultSortColumnIndex = -1;
 		for (int i = 0; i < columns.length; i++) {
 			final T column = columns[i];

 			if (supportsSorting) {
 				addColumnSelectionListener(column, new SelectionAdapter() {
 					@Override
 					public void widgetSelected(SelectionEvent e) {
 						int direction = getSortDirection();
 						if (getSortColumn() == column && direction != SWT.NONE) {
 							direction = (direction == SWT.DOWN) ? SWT.UP : SWT.NONE;
 						} else {
 							direction = SWT.DOWN;
 						}

 						setSortDirection(direction);
 						if (direction == SWT.NONE) {
 							setSortColumn(null);
 						} else {
 							setSortColumn(column);
 						}
 						viewer.refresh();
 					}
 				});
 				if (column == getSortColumn()) {
 					defaultSortColumnIndex = i;
 				}
 			}

 			MenuItem item = createMenuItem(headerMenu, column, i);
 			item.setEnabled(canHide(column));

 			defaults[i] = new ColumnState();
 			defaults[i].width = getWidth(column);

 		}

 		createRestoreDefaults(headerMenu);

 		defaultOrder = getColumnOrder();
 		defaultSortDirection = getSortDirection();

 		control.addListener(SWT.MenuDetect, new Listener() {
 			public void handleEvent(Event event) {
 				Menu menu = control.getMenu();
 				if (menu != null && menu != headerMenu) {
 					contextMenu = menu;
 				}

 				Display display = control.getDisplay();
 				Point pt = display.map(null, control, new Point(event.x, event.y));
 				Rectangle clientArea = getClientArea();
 				boolean header = clientArea.y <= pt.y && pt.y < (clientArea.y + getHeaderHeight());

 				control.setMenu(header ? headerMenu : contextMenu);
 			}
 		});

 		control.addDisposeListener(new DisposeListener() {
 			public void widgetDisposed(DisposeEvent event) {
 				save();
 			}
 		});
 	}

 	private boolean canHide(T column) {
 		Object canHide = column.getData(KEY_COLUMN_CAN_HIDE);
 		return !(canHide instanceof Boolean) || ((Boolean) canHide).booleanValue();
 	}

 	void initializeViewerSupport() {
 		initialize();
 		restore();

 		T[] columns = getColumns();
 		lastStates = new ColumnState[columns.length];
 		for (int i = 0; i < columns.length; i++) {
 			final T column = columns[i];
 			lastStates[i] = new ColumnState();
 			lastStates[i].width = getWidth(column);
 		}
 	}

 	private void restore() {
 		if (stateFile.exists()) {
 			try {
 				FileReader reader = new FileReader(stateFile);
 				try {
 					XmlMemento memento = XmlMemento.createReadRoot(reader);

 					XmlMemento[] children = memento.getChildren("Column"); //$NON-NLS-1$
 					int[] order = new int[children.length];
 					for (int i = 0; i < children.length; i++) {
 						T column = getColumn(i);
 						Integer widthInteger = children[i].getInteger("width"); //$NON-NLS-1$
 						if (widthInteger != null) {
 							int width = widthInteger;
 							// ensure that columns that may not be hidden have a non zero width
 							if (width >= 0 && (width > 0 || canHide(column))) {
 								setWidth(column, width);
 							}
 						}
 						headerMenu.getItem(i).setSelection(getWidth(column) > 0);
 						Integer orderInteger = children[i].getInteger("order"); //$NON-NLS-1$
 						order[i] = (orderInteger != null) ? orderInteger.intValue() : 0;
 						restoreAdditionalChildInfo(children[i], column);
 					}
 					try {
 						setColumnOrder(order);
 					} catch (IllegalArgumentException e) {
 						// ignore
 					}

 					XmlMemento child = memento.getChild("Sort"); //$NON-NLS-1$
 					if (child != null) {
 						int columnIndex = child.getInteger("column"); //$NON-NLS-1$
 						T column = getColumn(columnIndex);
 						setSortColumn(column);
 						setSortDirection(child.getInteger("direction")); //$NON-NLS-1$
 					}
 				} catch (Exception e) {
 					// ignore
 				} finally {
 					reader.close();
 				}
 			} catch (IOException e) {
 				// ignore
 			}

 			viewer.refresh();
 		} else {
 			T[] columns = getColumns();
 			for (int i = 0; i < columns.length; i++) {
 				T column = columns[i];
 				if (i < defaultVisibilities.length && !defaultVisibilities[i]) {
 					setWidth(column, 0);
 					headerMenu.getItem(i).setSelection(false);
 				}
 			}
 		}
 	}

 	private void restoreDefaults() {
 		for (int index = 0; index < defaults.length; index++) {
 			T column = getColumn(index);
 			if (index < defaultVisibilities.length && !defaultVisibilities[index]) {
 				setWidth(column, 0);
 			} else {
 				setWidth(column, defaults[index].width);
 			}
 			// update the menu
 			headerMenu.getItem(index).setSelection(getWidth(column) > 0);
 		}
 		setColumnOrder(defaultOrder);
 		if (defaultSortColumnIndex != -1) {
 			setSortColumn(getColumn(defaultSortColumnIndex));
 			setSortDirection(defaultSortDirection);
 		} else {
 			setSortColumn(null);
 		}
 		viewer.refresh();
 	}

 	private void save() {
 		XmlMemento memento = XmlMemento.createWriteRoot("Viewer"); //$NON-NLS-1$

 		int[] order = getColumnOrder();
 		T[] columns = getColumns();
 		for (int i = 0; i < columns.length; i++) {
 			T column = columns[i];
 			XmlMemento child = memento.createChild("Column"); //$NON-NLS-1$
 			child.putInteger("width", getWidth(column)); //$NON-NLS-1$
 			child.putInteger("order", order[i]); //$NON-NLS-1$
 			saveAdditionalChildInfo(child, column);
 		}

 		T sortColumn = getSortColumn();
 		if (sortColumn != null) {
 			XmlMemento child = memento.createChild("Sort"); //$NON-NLS-1$
 			child.putInteger("column", getColumnIndexOf(sortColumn)); //$NON-NLS-1$
 			child.putInteger("direction", getSortDirection()); //$NON-NLS-1$
 		}

 		try {
 			FileWriter writer = new FileWriter(stateFile);
 			try {
 				memento.save(writer);
 			} finally {
 				writer.close();
 			}
 		} catch (IOException e) {
 			// ignore
 		}
 	}

 	abstract void setColumnOrder(int[] order);

 	abstract void setColumnResizable(T column, boolean resizable);

 	abstract void setColumnWidth(T column, int width);

 	abstract void setSortColumn(T column);

 	abstract void setSortDirection(int direction);

 	private void setWidth(T column, int width) {
 		// if has column data, set that (pixel or weight)
 		ColumnLayoutData data = getColumnLayoutData(column);
 		AbstractColumnLayout columnLayout = getColumnLayout();
 		if (data != null && columnLayout != null) {
 			if (width == 0) {
 				columnLayout.setColumnData(column, new ColumnPixelData(width, data.resizable));
 			} else {
 				columnLayout.setColumnData(column, new ColumnWeightData(width, data.resizable));
 			}
 			control.getParent().layout();
 		} else {
 			setColumnWidth(column, width);
 		}
 		setColumnResizable(column, width > 0);
 	}

 	/**
 	 * @since 3.22
 	 */
 	protected void saveAdditionalChildInfo(XmlMemento child, T column) {
 	}

 	/**
 	 * @since 3.22
 	 */
 	protected void restoreAdditionalChildInfo(XmlMemento xmlMemento, T column) {
 	}

 	/**
 	 * @since 3.22
 	 */
 	protected Menu getHeaderMenu() {
 		return headerMenu;
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2010, 2011 Tasktop Technologies and others.
	*
	* This program and the accompanying materials are made available under the
	* terms of the Eclipse Public License v. 2.0 which is available at
	* https://www.eclipse.org/legal/epl-2.0
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Tasktop Technologies - initial API and implementation
	*******************************************************************************/

	package org.eclipse.mylyn.commons.ui;

	import java.io.File;
	import java.io.FileReader;
	import java.io.FileWriter;
	import java.io.IOException;

	import org.eclipse.core.runtime.Assert;
	import org.eclipse.jface.layout.AbstractColumnLayout;
	import org.eclipse.jface.util.Policy;
	import org.eclipse.jface.viewers.ColumnLayoutData;
	import org.eclipse.jface.viewers.ColumnPixelData;
	import org.eclipse.jface.viewers.ColumnViewer;
	import org.eclipse.jface.viewers.ColumnWeightData;
	import org.eclipse.mylyn.commons.core.XmlMemento;
	import org.eclipse.mylyn.internal.commons.ui.Messages;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.events.DisposeEvent;
	import org.eclipse.swt.events.DisposeListener;
	import org.eclipse.swt.events.SelectionAdapter;
	import org.eclipse.swt.events.SelectionEvent;
	import org.eclipse.swt.events.SelectionListener;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.graphics.Rectangle;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Event;
	import org.eclipse.swt.widgets.Item;
	import org.eclipse.swt.widgets.Listener;
	import org.eclipse.swt.widgets.Menu;
	import org.eclipse.swt.widgets.MenuItem;

	/**
	* Provides an abstract implementation for persisting the column and sorting state of a {@link ColumnViewer}.
	*
	* @author Shawn Minto
	* @author Steffen Pingel
	* @since 3.7
	*/
	public abstract class AbstractColumnViewerSupport<T extends Item> {

	private static class ColumnState {
	// this represents the width of the column or the weight if it was weight data
	int width;
	}

	public static final String KEY_COLUMN_CAN_HIDE = "org.eclipse.mylyn.column.viewer.support.column.can.hide"; //$NON-NLS-1$

	// from AbstractColumnLayout
	private static final String KEY_LAYOUT_DATA = Policy.JFACE + ".LAYOUT_DATA"; //$NON-NLS-1$

	public static final String KEY_SUPPORTS_SORTING = "org.eclipse.mylyn.column.viewer.support.sorting"; //$NON-NLS-1$

	private Menu contextMenu;

	private final Control control;

	private int[] defaultOrder;

	private ColumnState[] defaults;

	private int defaultSortColumnIndex;

	private int defaultSortDirection;

	private final boolean[] defaultVisibilities;

	private final Menu headerMenu;

	private ColumnState[] lastStates;

	private final File stateFile;

	private boolean supportsSorting;

	private final ColumnViewer viewer;

	public AbstractColumnViewerSupport(ColumnViewer viewer, File stateFile) {
	this(viewer, stateFile, new boolean[0]);
	}

	public AbstractColumnViewerSupport(ColumnViewer viewer, File stateFile, boolean[] defaultVisibilities) {
	Assert.isNotNull(viewer);
	Assert.isNotNull(stateFile);
	Assert.isNotNull(defaultVisibilities);
	Object supportSort = viewer.getControl().getData(KEY_SUPPORTS_SORTING);
	if (supportSort instanceof Boolean) {
	supportsSorting = (Boolean) supportSort;
	} else {
	supportsSorting = true;
	}
	this.defaultVisibilities = defaultVisibilities;
	this.viewer = viewer;
	this.stateFile = stateFile;

	control = viewer.getControl();

	Composite parent = viewer.getControl().getParent();
	headerMenu = new Menu(parent);
	}

	abstract void addColumnSelectionListener(T column, SelectionListener selectionListener);

	private MenuItem createMenuItem(Menu parent, final T column, final int i) {
	final MenuItem item = new MenuItem(parent, SWT.CHECK);
	item.setText(column.getText());
	item.setSelection(getWidth(column) > 0);
	item.addListener(SWT.Selection, new Listener() {
	public void handleEvent(Event event) {
	int lastWidth = getWidth(column);
	if (lastWidth != 0) {
	lastStates[i].width = lastWidth;
	}
	if (lastStates[i].width == 0) {
	// if the user shrunk it to 0, use the default
	lastStates[i].width = defaults[i].width;
	}
	if (lastStates[i].width == 0) {
	// if the default and the last width was 0, then set to 150 pixels
	lastStates[i].width = 150;
	}
	if (item.getSelection()) {
	setWidth(column, lastStates[i].width);
	} else {
	setWidth(column, 0);
	}
	}
	});
	return item;
	}

	private void createRestoreDefaults(Menu parent) {

	new MenuItem(parent, SWT.SEPARATOR);

	final MenuItem restoreDefaults = new MenuItem(parent, SWT.PUSH);
	restoreDefaults.setText(Messages.AbstractColumnViewerSupport_Restore_defaults);
	restoreDefaults.addListener(SWT.Selection, new Listener() {
	public void handleEvent(Event event) {
	restoreDefaults();
	}
	});
	}

	abstract Rectangle getClientArea();

	abstract T getColumn(int index);

	abstract int getColumnIndexOf(T column);

	abstract AbstractColumnLayout getColumnLayout();

	private ColumnLayoutData getColumnLayoutData(Item column) {
	Object data = column.getData(KEY_LAYOUT_DATA);
	if (data instanceof ColumnLayoutData) {
	return (ColumnLayoutData) data;
	} else {
	return null;
	}
	}

	abstract int[] getColumnOrder();

	abstract T[] getColumns();

	abstract int getColumnWidth(T column);

	abstract int getHeaderHeight();

	abstract T getSortColumn();

	abstract int getSortDirection();

	private int getWidth(T column) {
	ColumnLayoutData data = getColumnLayoutData(column);
	AbstractColumnLayout columnLayout = getColumnLayout();
	if (data != null && columnLayout != null) {
	if (data instanceof ColumnWeightData) {
	return ((ColumnWeightData) data).weight;
	} else if (data instanceof ColumnPixelData) {
	// turn this into a weighted width
	int width = ((ColumnPixelData) data).width;
	int totalWidth = control.getSize().x;
	if (totalWidth == 0) {
	return width;
	} else {
	return (width * 100) / totalWidth;
	}
	} else {
	// we dont know
	return getColumnWidth(column);
	}
	} else {
	// if has column data, use that (pixel or weight)
	return getColumnWidth(column);
	}
	}

	private void initialize() {
	T[] columns = getColumns();
	defaults = new ColumnState[columns.length];
	defaultSortColumnIndex = -1;
	for (int i = 0; i < columns.length; i++) {
	final T column = columns[i];

	if (supportsSorting) {
	addColumnSelectionListener(column, new SelectionAdapter() {
	@Override
	public void widgetSelected(SelectionEvent e) {
	int direction = getSortDirection();
	if (getSortColumn() == column && direction != SWT.NONE) {
	direction = (direction == SWT.DOWN) ? SWT.UP : SWT.NONE;
	} else {
	direction = SWT.DOWN;
	}

	setSortDirection(direction);
	if (direction == SWT.NONE) {
	setSortColumn(null);
	} else {
	setSortColumn(column);
	}
	viewer.refresh();
	}
	});
	if (column == getSortColumn()) {
	defaultSortColumnIndex = i;
	}
	}

	MenuItem item = createMenuItem(headerMenu, column, i);
	item.setEnabled(canHide(column));

	defaults[i] = new ColumnState();
	defaults[i].width = getWidth(column);

	}

	createRestoreDefaults(headerMenu);

	defaultOrder = getColumnOrder();
	defaultSortDirection = getSortDirection();

	control.addListener(SWT.MenuDetect, new Listener() {
	public void handleEvent(Event event) {
	Menu menu = control.getMenu();
	if (menu != null && menu != headerMenu) {
	contextMenu = menu;
	}

	Display display = control.getDisplay();
	Point pt = display.map(null, control, new Point(event.x, event.y));
	Rectangle clientArea = getClientArea();
	boolean header = clientArea.y <= pt.y && pt.y < (clientArea.y + getHeaderHeight());

	control.setMenu(header ? headerMenu : contextMenu);
	}
	});

	control.addDisposeListener(new DisposeListener() {
	public void widgetDisposed(DisposeEvent event) {
	save();
	}
	});
	}

	private boolean canHide(T column) {
	Object canHide = column.getData(KEY_COLUMN_CAN_HIDE);
	return !(canHide instanceof Boolean) \|\| ((Boolean) canHide).booleanValue();
	}

	void initializeViewerSupport() {
	initialize();
	restore();

	T[] columns = getColumns();
	lastStates = new ColumnState[columns.length];
	for (int i = 0; i < columns.length; i++) {
	final T column = columns[i];
	lastStates[i] = new ColumnState();
	lastStates[i].width = getWidth(column);
	}
	}

	private void restore() {
	if (stateFile.exists()) {
	try {
	FileReader reader = new FileReader(stateFile);
	try {
	XmlMemento memento = XmlMemento.createReadRoot(reader);

	XmlMemento[] children = memento.getChildren("Column"); //$NON-NLS-1$
	int[] order = new int[children.length];
	for (int i = 0; i < children.length; i++) {
	T column = getColumn(i);
	Integer widthInteger = children[i].getInteger("width"); //$NON-NLS-1$
	if (widthInteger != null) {
	int width = widthInteger;
	// ensure that columns that may not be hidden have a non zero width
	if (width >= 0 && (width > 0 \|\| canHide(column))) {
	setWidth(column, width);
	}
	}
	headerMenu.getItem(i).setSelection(getWidth(column) > 0);
	Integer orderInteger = children[i].getInteger("order"); //$NON-NLS-1$
	order[i] = (orderInteger != null) ? orderInteger.intValue() : 0;
	restoreAdditionalChildInfo(children[i], column);
	}
	try {
	setColumnOrder(order);
	} catch (IllegalArgumentException e) {
	// ignore
	}

	XmlMemento child = memento.getChild("Sort"); //$NON-NLS-1$
	if (child != null) {
	int columnIndex = child.getInteger("column"); //$NON-NLS-1$
	T column = getColumn(columnIndex);
	setSortColumn(column);
	setSortDirection(child.getInteger("direction")); //$NON-NLS-1$
	}
	} catch (Exception e) {
	// ignore
	} finally {
	reader.close();
	}
	} catch (IOException e) {
	// ignore
	}

	viewer.refresh();
	} else {
	T[] columns = getColumns();
	for (int i = 0; i < columns.length; i++) {
	T column = columns[i];
	if (i < defaultVisibilities.length && !defaultVisibilities[i]) {
	setWidth(column, 0);
	headerMenu.getItem(i).setSelection(false);
	}
	}
	}
	}

	private void restoreDefaults() {
	for (int index = 0; index < defaults.length; index++) {
	T column = getColumn(index);
	if (index < defaultVisibilities.length && !defaultVisibilities[index]) {
	setWidth(column, 0);
	} else {
	setWidth(column, defaults[index].width);
	}
	// update the menu
	headerMenu.getItem(index).setSelection(getWidth(column) > 0);
	}
	setColumnOrder(defaultOrder);
	if (defaultSortColumnIndex != -1) {
	setSortColumn(getColumn(defaultSortColumnIndex));
	setSortDirection(defaultSortDirection);
	} else {
	setSortColumn(null);
	}
	viewer.refresh();
	}

	private void save() {
	XmlMemento memento = XmlMemento.createWriteRoot("Viewer"); //$NON-NLS-1$

	int[] order = getColumnOrder();
	T[] columns = getColumns();
	for (int i = 0; i < columns.length; i++) {
	T column = columns[i];
	XmlMemento child = memento.createChild("Column"); //$NON-NLS-1$
	child.putInteger("width", getWidth(column)); //$NON-NLS-1$
	child.putInteger("order", order[i]); //$NON-NLS-1$
	saveAdditionalChildInfo(child, column);
	}

	T sortColumn = getSortColumn();
	if (sortColumn != null) {
	XmlMemento child = memento.createChild("Sort"); //$NON-NLS-1$
	child.putInteger("column", getColumnIndexOf(sortColumn)); //$NON-NLS-1$
	child.putInteger("direction", getSortDirection()); //$NON-NLS-1$
	}

	try {
	FileWriter writer = new FileWriter(stateFile);
	try {
	memento.save(writer);
	} finally {
	writer.close();
	}
	} catch (IOException e) {
	// ignore
	}
	}

	abstract void setColumnOrder(int[] order);

	abstract void setColumnResizable(T column, boolean resizable);

	abstract void setColumnWidth(T column, int width);

	abstract void setSortColumn(T column);

	abstract void setSortDirection(int direction);

	private void setWidth(T column, int width) {
	// if has column data, set that (pixel or weight)
	ColumnLayoutData data = getColumnLayoutData(column);
	AbstractColumnLayout columnLayout = getColumnLayout();
	if (data != null && columnLayout != null) {
	if (width == 0) {
	columnLayout.setColumnData(column, new ColumnPixelData(width, data.resizable));
	} else {
	columnLayout.setColumnData(column, new ColumnWeightData(width, data.resizable));
	}
	control.getParent().layout();
	} else {
	setColumnWidth(column, width);
	}
	setColumnResizable(column, width > 0);
	}

	/**
	* @since 3.22
	*/
	protected void saveAdditionalChildInfo(XmlMemento child, T column) {
	}

	/**
	* @since 3.22
	*/
	protected void restoreAdditionalChildInfo(XmlMemento xmlMemento, T column) {
	}

	/**
	* @since 3.22
	*/
	protected Menu getHeaderMenu() {
	return headerMenu;
	}

	}